News Release 29-Aug-2025
Thawing permafrost raised carbon dioxide levels after the last ice age
Peer-Reviewed Publication
University of Gothenburg

Carbon dioxide levels in the atmosphere vary naturally between ice ages and interglacial periods. A new study by researchers at the University of Gothenburg shows that an unexpectedly large proportion of carbon dioxide emissions after the ice age may have come from thawing permafrost.

For a long time, it was the shifts between ice ages and interglacial periods that determined how much carbon dioxide was in the atmosphere. During ice ages, CO₂ levels fell, only to rise by around 100 ppm (parts per million) during interglacial periods. Previously, the main reason for this was thought to be that warmer and more mixed oceans cannot store as much carbon and therefore release it into the atmosphere between ice ages.

However, new research from the University of Gothenburg shows that thawing permafrost may have accounted for a significant proportion of carbon dioxide emissions.

"We have concluded that land north of the Tropic of Cancer, 23.5 degrees north, emitted a lot of carbon when the average temperature rose in the northern hemisphere after our last ice age. We estimate that this carbon exchange may have accounted for almost half of the rising carbon dioxide levels in the atmosphere," says Amelie Lindgren, researcher in ecosystem science at the University of Gothenburg.

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